Tuesday, January 03, 2017

The NetworkManager instantiates a Player prefab. This is your Player Object.

In a two player game, your GameObjects exist conceptually in 3 places, and logically in 2 places. An object exists on each game client, and on the game server. If the game server is also a client, it is called a host, and it shares the GameObject with the client.

By default:
- only methods on components on the Player Object can have the [Command] attribute.
- you can only call [Command] methods from other methods on the Player Object.

It is hard to see which code is server code, and which is client code. I recommend using the [Server] and [Client] attributes liberally to add this information to the source code. When this attribute cannot be applied to a method (only NetworkBehaviours support this attribute) then add the attribute inside a comment.

The NetworkTransform does not provide interpolation when in Transform mode, only when using RigidBody mode. You will need to write this code yourself using [SyncVar].

For fast iterative development, keep the NetworkManager in your development scene, and add the NetworkManagerHUD component. Set this scene as your startup scene, then Build and Run, choose Host or Client from the GUI, then press Play in the editor, and choose Host or Client.

NetworkServer.Spawn only create an instance on the client, and sets it's transform component to match the server. You will have to do any other configuration on this object via a secondary [ClientRpc] call.

Using the below test script, using GetComponent is about 3x slower than using a direct reference. Caching the return calue in a Dictionary, is slightly faster.

A typical result for me is 232 GetComponent(), 74 for private field and 201 for a dictionary lookup. If you use a builtin Unity type, like Transform, GetComponent is twice as fast.

I made sure the compiler was not optimising out my tests by putting in some fake 'xyzzy' work which is not included in the timing.

Why this simple test? I'm proving to myself it is not terribly bad to use a GetComponent call in an update loop, or keep a Dictionary cache. The call itself is so fast (0.000000232 seconds) that there is really no issue using it a few times inside an update loop.